Double Metal Cyanide Catalysts for Propylene Oxide Copolymerization
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Solution Overview
Problem
Zinc hexacyanometalates used for epoxide/carbon dioxide copolymerization produce undesired by-products like propylene carbonate, requiring low temperatures that reduce catalyst activity.
Innovation Solution
Tetracyanometallate containing double metal cyanide complexes catalyze the copolymerization of propylene oxide and carbon dioxide without forming propylene carbonate, enabling both non-alternating copolymerization and homopolymerization of propylene oxide, using catalysts like anhydrous Co[M(CN)4] where M is Ni, Pd, or Pt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If zinc hexacyanometalates are used for epoxide/carbon dioxide copolymerization, then copolymerization can be achieved, but undesired by-product propylene carbonate is formed requiring purification
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by replacing zinc hexacyanometalates with tetracyanometallate containing double metal cyanide complexes. This parameter change in catalyst composition fundamentally alters the reaction pathway to eliminate propylene carbonate formation while maintaining copolymerization capability.
2Object-generated harmful factors
If low temperatures are used to prevent propylene carbonate formation with zinc hexacyanometalates, then by-product formation is reduced, but catalyst activity is significantly reduced
Solution Approach 1:
The patent changes the temperature parameter from low temperature operation to higher temperature operation by implementing a new catalyst system. The tetracyanometallate containing double metal cyanide complexes maintain high activity at elevated temperatures while preventing propylene carbonate formation, thus resolving the temperature-related contradiction.
Solution Approach 2:
The patent creates a new catalyst system that copies and improves upon the functionality of zinc hexacyanometalates. The tetracyanometallate containing double metal cyanide complexes replicate the copolymerization capability while eliminating the temperature limitation and by-product formation issues.
3Quantity of substance
If zinc hexacyanometalates are used for copolymerization, then copolymer production is achieved, but propylene carbonate by-product requires additional purification steps
Solution Approach 1:
The patent extracts and eliminates the harmful by-product formation pathway by replacing the zinc hexacyanometalate catalyst with tetracyanometallate containing double metal cyanide complexes. This removal of the propylene carbonate formation mechanism simplifies the overall process by eliminating the need for purification steps specifically designed to remove this by-product.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for the production of polyether-polycarbonate and poly(propylene oxide) with controlled molecular weights and regioregularity, avoiding propylene carbonate formation and maintaining catalyst activity at higher temperatures, making the process more efficient and effective.
Implementation Method 1
tetracyanometallate containing double metal cyanide complexes readily catalyzed the copolymerization of propylene oxide and carbon dioxide
Implementation Method 2
These complexes are also functional to catalyze the homopolymerization of propylene oxide
Data Source
AI summary
Copolymers of propylene oxide and carbon dioxide and homopolymers of propylene oxide are made using two dimensional double metal cyanide complexes having the formula Co[M(CN)4] or hydrated or partially dehydrated form thereof. There is no propylene carbonate by product in the copolymerization.